On Wed, Feb 03, 2021 at 11:04:04AM +0100, Peter Krempa wrote:
> On Tue, Feb 02, 2021 at 16:04:12 +0100, Pavel Hrdina wrote:
> > Implements QEMU support for vhost-user-blk together with live
> > hotplug/unplug.
> >
> > Signed-off-by: Pavel Hrdina <phrdina@xxxxxxxxxx>
> > ---
> > src/qemu/qemu_block.c | 16 ++++
> > src/qemu/qemu_block.h | 5 +
> > src/qemu/qemu_command.c | 91 +++++++++++++++++--
> > src/qemu/qemu_command.h | 8 ++
> > src/qemu/qemu_domain.c | 5 +
> > src/qemu/qemu_hotplug.c | 5 +-
> > src/qemu/qemu_validate.c | 13 +++
> > .../disk-vhostuser.x86_64-latest.args | 41 +++++++++
> > tests/qemuxml2argvtest.c | 1 +
> > 9 files changed, 176 insertions(+), 9 deletions(-)
> > create mode 100644 tests/qemuxml2argvdata/disk-vhostuser.x86_64-latest.args
>
> [...]
>
> > diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
> > index 3e652e18b7..059126cfeb 100644
> > --- a/src/qemu/qemu_command.c
> > +++ b/src/qemu/qemu_command.c
> > @@ -1712,9 +1712,16 @@ qemuBuildDiskDeviceStr(const virDomainDef *def,
> > break;
> >
> > case VIR_DOMAIN_DISK_BUS_VIRTIO:
> > - if (qemuBuildVirtioDevStr(&opt, "virtio-blk", qemuCaps,
> > - VIR_DOMAIN_DEVICE_DISK, disk) < 0) {
> > - return NULL;
> > + if (virStorageSourceGetActualType(disk->src) == VIR_STORAGE_TYPE_VHOST_USER) {
> > + if (qemuBuildVirtioDevStr(&opt, "vhost-user-blk", qemuCaps,
> > + VIR_DOMAIN_DEVICE_DISK, disk) < 0) {
> > + return NULL;
> > + }
> > + } else {
> > + if (qemuBuildVirtioDevStr(&opt, "virtio-blk", qemuCaps,
> > + VIR_DOMAIN_DEVICE_DISK, disk) < 0) {
> > + return NULL;
> > + }
>
> Preferably, add a temporary string holding either "vhost-user-blk" or
> "virtio-blk" and call qemuBuildVirtioDevStr just once, since all other
> arguments are the same.
This would require adding one level of nesting because of the temporary
variable or I would have to define the variable at the top of the
function. Not sure if it makes it better.
>
> > }
> >
> > if (disk->iothread)
>
> [...]
>
>
> > diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
> > index 0c078a9388..aa6d539610 100644
> > --- a/src/qemu/qemu_domain.c
> > +++ b/src/qemu/qemu_domain.c
> > @@ -10581,6 +10581,11 @@ qemuDomainPrepareDiskSource(virDomainDiskDefPtr disk,
> > disk->src->format = VIR_STORAGE_FILE_RAW;
> > }
> >
> > + /* Nothing else to prepare as it will use -chardev instead
> > + * of -blockdev/-drive option. */
> > + if (disk->src->type == VIR_STORAGE_TYPE_VHOST_USER)
> > + return 0;
>
> The code above sets 'format' for storage pool backed disks, but since
> format isn't something we'd be setting for vhost-user this exemption
> should be at the beginning of the function.
Fixed.
> > +
> > if (virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_BLOCKDEV) &&
> > !qemuDiskBusIsSD(disk->bus)) {
> > if (qemuDomainPrepareDiskSourceBlockdev(disk, priv, cfg) < 0)
>
>
> Missing stuff from this commit:
>
> - hot-unplug support
> - see qemuDomainRemoveDiskDevice where the chardev isn't deleted
> - blockjob lockout
> - qemuDomainDiskBlockJobIsSupported
> - block iotune lockout
> - possible better lockout for qemuDomainBlockPeek
> - it will barf either that the file is not 'raw' or that it can't be
> initialized
> - possible better lockout for qemuDomainSetBlockThreshold
> - "threshold currently can't be set for block device '%s'" <- it
> will never be possible
> - lockout for qemuDomainGetBlockInfo
> - lockout for qemuDomainBlockResize
> - lockout for qemuDomainBlockStats(Flags)
> - handling in bulk stats (qemuDomainGetStatsBlockExportDisk ?)
Well, that's a lot of missing things, thanks for the pointers, I'll look
into it.
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